Top formed packaging

ABSTRACT

A packaging machine may package irregularly shaped food products such that a heat-sensitive lidding material is thermoformed to generally conform to the configuration of the food product.

[0001] This application claims the benefit of U.S. Provisional Application No. 60/373,867 filed Apr. 19, 2002.

BACKGROUND

[0002] The present invention relates generally to food packaging and in particular to food packaging relating to perishable foods.

[0003] For many years, retailers have sold perishable food products such as fresh meats in “case ready” packaging. Generally, case ready packaging is based upon a central packaging location where animals are slaughtered and cut into retail cuts. Before distribution to the retail outlets, the meat is packaged in a modified atmosphere packaging. Thus, retail outlets benefit because they do not have to employ butchers for on-sight cutting and packaging of the perishable food products.

[0004] One drawback to case ready packaging is a mismatch between the size of the food product and the dimensions of the tray that the food product is contained in. For example, a perishable food product may have an irregular shape with variable dimensions, such as a cut of beef or poultry. In contrast, the preformed trays used for packaging the irregularly shaped food products have a predetermined fixed regular shape. Thus, the food product is generally contained in a preformed tray that is larger than the food product. As a result, there is substantial headspace between the product and the clear lidding material when the food product is sealed in its final package.

[0005] Generally, consumers do not readily accept case ready packaging with a substantial headspace because they perceive the package as being only half full.

[0006] Thus, there is a continuing need for a case ready package with minimal, if any headspace.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a sectional partial view of a package according to embodiments of the present invention;

[0008]FIG. 2 is a sectional partial view of a heat-sealing platen and a female thermoforming mold that is housed within the platen according to embodiments of the present invention;

[0009]FIG. 3 is a sectional view of a thermoforming assembly according to embodiments of the present invention; and

[0010]FIG. 4 is schematic view of a packaging machine that may be adapted to produce a packaged food product according to embodiments of the present invention.

DETAILED DESCRIPTION

[0011] Referring to FIG. 1, a completed food package 10 includes a food item 12 that is situated within a preformed tray 14 having a lidding material 16 thermoformed and heat-sealed 18 thereto. The tray 14 may include a base 20, a layer 22 and a flange 24. In embodiments of the present invention, the lidding material 16 may be hermetically heat-sealed 18 to the flange 24.

[0012] The base 20 may be a conventional base made from material such as plastic or paperboard. Likewise, the layer 22 may be a conventional layer that is coated or laminated to the base 20. The food item 12 may be any food item including perishable foods such as meat and poultry. According to embodiments of the present invention, the lidding material 16 may be any flexible heat-sensitive film that is capable of being thermoformed.

[0013] Generally, according to embodiments of the present invention, the lidding material 16 is positioned over the tray 14. Thereafter, the lidding material 16 is thermoformed to conform to the general shape of the food product 12 and is heat-sealed to the flange 24.

[0014] Referring to FIG. 2, a thermoforming device 30 may include a heat-sealing platen 32 and a thermoforming mold 34. The heat-sealing platen 32 may include an exterior wall 36, an interior wall 38 and a base 40. The interior wall 38 and base 40 define an indentation 42 in which the thermoforming mold 34 is situated. Additionally, the heat-sealing platen 32 may include one or more apertures 44 and a heating element 46. The heating element 46 may be any conventional heating element such as an electric heating element. Generally, the heating element 46 is situated within the base 40 of the platen 32 to heat the platen 32 to a temperature that is high enough to seal the lidding material 16 to the tray 14.

[0015] The thermoforming mold 34 may include a side 48 that is contoured, an opposing side 50 that is not contoured, and two opposing walls 52. Moreover, the thermoforming mold 34 may include a plurality of apertures 54 that extend between the contoured side 48 and the side 50 that is not contoured. Generally, the thermoforming mold 34 is situated within the indentation 42 such the side 50 that is not contoured is adjacent to the platen 32 whereas the contoured side 48 faces away from the platen 32.

[0016] One or more bolts 56 may be utilized to attach the thermoforming mold 34 to the heat-sealing platen 32. In embodiments of the present invention, a spacer 58 may be situated between the thermoforming mold 34 and the heat-sealing platen 32. The spacer 58 may be heat resistant or insulated. Generally, the bolts 56 may extend downwardly through the platen 32 and the spacer 58 to attach the mold 34 to the platen 32. Accordingly, a void area 60 is provided between the platen 32 and the mold 34 due to the spacer 58 spacing the two apart. The void area 60 between the platen 32 and the mold 34 creates an area of insulation. Thus, the heat-sealing platen 32 may operate at a temperature that is greater than that of the mold 34. The mold 34 may be independently heated by electrical resistance as an example.

[0017] Moreover, the void area 60 allows air to escape entrapment from the area between the lidding material 16 and the mold 34 via the apertures 54. Similarly, air in the void area 60 may be released via the apertures 44 in the platen 32 to an area thereabove (FIG. 3).

[0018] Referring to FIG. 3, a thermoforming assembly 62 includes an upper section 64 and a lower section 66, each defining an upper chamber 68 and a lower chamber 70, respectively. The thermoforming device 30 is housed within the upper chamber 68.

[0019] When heat-sealing is desired, a tray 14 carrying a food product 12 is transported to the thermoforming assembly 62 by way of a tray carrier 72. Similarly, the lidding material 16 is delivered to the thermoforming assembly 62 by conventional means (FIG. 4). When properly positioned, the thermoforming mold 34 is directly over the tray 14 containing the food product 12.

[0020] An external vacuum source 74 is coupled to both the upper section 64 and the lower section 66 of the thermoforming assembly 62 and is in communication with chambers 68 and 70. The coupling of the sections 64 and 66 to the vacuum source 74 may be by conventional means. Valves 76 and 78, such as in-line valves, may be utilized to regulate the vacuum to the upper and lower chambers 68 and 70 respectively. For example, when not in use the inline valves 76 and 78 are in the off position whereas when access to the vacuum source is desired, the valves 76 and 78 may be in the open position.

[0021] The upper section 64 is also coupled to a source 80 of ambient atmosphere. Articulation of valve 82 may regulate the connection to the ambient atmosphere so that the chamber 68 may be in selective communication with the ambient atmosphere. Additionally, a source 84 of positive pressure modified atmospheric gas 84 may be in communication with the lower chamber 70 of the thermoforming assembly. Communication is selective in that a valve 86, such as an in-line valve, may be articulated to regulate gas flow.

[0022] In operation, a food filled tray 14 may be positioned within the interior of the assembly 62. At the same time, lidding material 16 may be delivered to the interior of assembly 62. The lidding material 16 should be of sufficient width to fully cover the tray carrier 72. Further, the lidding material 16 should be positioned directly over the preformed tray 14. Thereafter, the upper section 64 and lower section 66 are moved toward each other to close the assembly 62. The tray carrier 72 and lidding material 16 are between the upper section 64 and the lower section 66 of the assembly 62. Thus, upon closure of the assembly 62, the tray carrier 72 and the thermoformable lidding 16 are clamped between the two sections 64 and 66. Moreover, a barrier is created to the outside atmosphere, which allows the chambers 68 and 70 to act as a vacuum chamber. Thereafter, valve 76 is opened to the vacuum source 74 to cause a pressure differential above and below the thermoformable lidding material 16. This pressure differential causes at least that portion of the lidding material 16 over the food product 12 to lift in the direction of the female thermoforming mold 34. Because heat radiates from the female thermoforming mold 34, the flexible lidding material 16 becomes formable. Thereafter, the valve 78 is opened to the vacuum source 74 to allow for the evacuation of the ambient atmosphere within the confines of the preformed tray 14. After a predetermined level of evacuation is satisfied, valves 76 and 78 are closed. To complete the thermoforming of the lidding material 16 to the mold 34, valve 86 is opened, which allows for the introduction of a positive pressure modified atmospheric gas into the chamber 70. As a result, the already heated thermoformable lidding material 16 is forced into direct contact with the mold 34 thereby stretching the film as well.

[0023] Once the preformed tray 14 is filled with a satisfactory volume of modified atmosphere, the valve 86 is closed. Atmospheric pressure is then introduced into the chamber 68 by opening the valve 82. Because the atmospheric pressure is higher than that of the chamber 68, the thermoforming lidding material 16 is forced into conformity with the food product 12. As the lidding 16 cools it shrinks to permanently conform to the shape of the food product 12.

[0024] Further, as the atmospheric pressure enters the chamber 68, the heated platen 32 is driven into contact with that portion of the thermoforming lidding material 16 in contact with the flange 24 of the tray 14. This brings the lidding material 16 to a temperature that is suitable for hermetic heat-sealing to the flange 24 of the preformed tray 14.

[0025] Referring to FIG. 4, a packaging machine 90 may include the thermoforming assembly 62, tray carrier 72 and rolls 92 and 94 of lidding material 16. Generally, a tray 14 may be placed on the tray carrier 72 and filled with a food product 12. Thereafter, the filled tray 14 is transported to the thermoforming assembly 62. At the same time, the lidding material 16 is delivered to and away from the thermoforming assembly 62 by way of rolls 92 and 94 respectively. The tray carrier 72 and lidding material 16 generally move in the direction of arrow “A”.

[0026] Once situated within the thermoforming assembly 62, the lidding material 16 may be thermoformed to conform to the configuration of the food product within the tray 14 and heat sealed 18 to the flange 24 of the tray 14. Thereafter, the excess lidding material 16 external to the flange 24 may be removed via a severing device 96. In some embodiments, the severing device 96 may be part of the thermoforming assembly 62. However, in other embodiments of the present invention the severing device 96 may be separate from the thermoforming assembly 62. Thereafter, the finished package 10 (FIG. 1) is transported to an exit station 98 where the package 10 is removed. The package 10 may be removed either manually or automatically as the case may be.

[0027] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention. 

What is claimed is:
 1. A method of generating a package containing a food product, the package including a preformed tray defining a peripheral flange and a thermoformable flexible lidding material, the method comprising the steps of: mounting a female thermoforming mold within the perimeter of a heat-sealing platen allowing an insulated area between the female thermoforming mold and the heat-sealing platen sufficient to cause a differential in temperature between the heat-sealing platen and the female thermoforming mold; thermoforming a flexible lidding into the general configuration of said female thermoforming mold; and ventilation to atmosphere through said thermoforming mold so that the thermoformable flexible lidding material generally conforms to the configuration of the food product contained within a preformed tray.
 2. The method as defined in claim 1 wherein the female thermoforming mold is mounted within the perimeter of a heat-sealing platen so as to allow for a void area between the female thermoforming mold and the heat-sealing platen.
 3. The method as defined in claim 1 wherein the ventilation to atmosphere is replaced with ventilation via compressed air.
 4. A method of manufacturing a packaging device comprising: providing a heat-sealing platen, said platen having an exterior wall, an interior wall and a base; disposing a thermoforming mold within the boundary defined by the interior wall of said platen; and spacing said mold apart from said platen.
 5. The method of claim 4 wherein providing a heat-sealing platen includes providing at least one aperture in said base.
 6. The method of claim 4 wherein disposing a thermoforming mold within the boundary defined by the interior wall includes disposing a female thermoforming mold having a plurality of apertures.
 7. The method of claim 4 further including providing an insulative spacer to space said mold apart from said platen.
 8. The method of claim 7 further including bolting said thermoforming mold to said platen such that a bolt secures said spacer between said mold and said platen.
 9. The method of claim 4 further including housing said heat-sealing platen and said thermoforming mold within a vacuum chamber.
 10. The method of claim 9 further including providing a vacuum source, a source for producing a positive pressure modified atmosphere and a vent to the ambient atmosphere to said vacuum chamber.
 11. A packaging apparatus comprising: a vacuum chamber; a first heated member disposed within said vacuum chamber; and a vacuum source coupled to said vacuum chamber.
 12. The apparatus of claim 11 further including a second heated member coupled to said first heated member.
 13. The apparatus of claim 12 further including a heat resistant spacer disposed between said first and second heated members.
 14. The apparatus of claim 13 wherein said first heated member is a female thermoforming mold.
 15. The apparatus of claim 14 wherein said second heated member is a platen.
 16. The apparatus of claim 15 further including a bolt to couple said mold to said platen and to secure said spacer there between.
 17. The apparatus of claim 11 further including a source to provide a positive pressure modified atmosphere coupled to said vacuum chamber.
 18. The apparatus if claim 17 further including a vent to the ambient atmosphere coupled to said chamber.
 19. An apparatus for packaging food products comprising: an upper housing defining a first chamber; a lower housing defining a second chamber, said lower housing opposite said upper housing; a heat-sealing platen disposed within said upper chamber; a thermoforming mold coupled to said platen; a spacer disposed between said mold and said platen; a vacuum source in communication with said upper and lower chambers; a source for positive pressure modified atmosphere in communication with said lower chamber; and a vent to ambient atmosphere in communication with said upper chamber.
 20. The apparatus of claim 19 further including at least one bolt to attach said mold to said platen and to secure said spacer between said mold and said platen.
 21. The apparatus of claim 19 further including a severing device housed within said upper chamber.
 22. The apparatus of claim 19 further including a tray carrier to transport said food package to said upper and lower housings.
 23. The apparatus of claim 19 wherein said platen includes an interior wall, an exterior wall and a base.
 24. The apparatus of claim 23 further including disposing said mold within the boundary defined by the interior wall of said platen.
 25. The apparatus of claim 19 wherein said platen includes at least one aperture.
 26. The apparatus of claim 19 wherein said platen is spaced apart from said upper housing.
 27. A method of packaging a food product comprising: using a tray carrier, positioning a preformed tray containing a food product within a vacuum chamber, said vacuum chamber including a heat-sealing platen with a female thermoforming mold coupled to said platen; positioning a sheet of lidding material over said tray; thermoforming said lidding material into the general configuration of the female thermoforming mold; and ventilating to atmosphere such that said lidding material generally conforms to the configuration of the food product contained within said tray.
 28. The method of claim 27 wherein thermoforming said lidding material includes creating a pressure differential across said lidding material to cause that portion of the lidding material over the food product to lift in the direction of said mold.
 29. The method of claim 28 further including evacuating ambient atmosphere from said tray.
 30. The method of claim 29 further including introducing a positive pressure modified atmosphere gas into said chamber to force the lidding material into direct contact with the mold.
 31. The method of claim 30 further including heating said platen to hermetically heat-seal said lidding material to said tray.
 32. The method of claim 31 further including heating said mold.
 33. The method of claim 32 further including creating a temperature differential between said heat-sealing platen and said mold.
 34. The method of claim 33 further including driving said platen into contact with said lidding material to heat-seal said lidding material to the periphery of said tray.
 35. The method of claim 27 further including severing the excess lidding material from the perimeter of the tray.
 36. A package for food products comprising: a tray; and a flexible lidding material that is stretched, heated and lifted away from a food product situated within said tray.
 37. The package of claim 36 wherein said lidding material is cooled and conformed to the surface of said food product.
 38. The package of claim 37 wherein said lidding material is heat-sealed to a flange on said tray.
 39. A method of packaging comprising: in a sealed chamber, positioning a sheet of flexible lidding material over a tray containing a food product; causing said lidding material to come into contact with a female thermoforming mold situated within said chamber; and forcing said lidding material into conformity with the food product.
 40. The method of claim 39 further including heating said lidding material.
 41. The method of claim 39 wherein causing said lidding material to come into contact with a female thermoforming mold includes creating a pressure differential across said lidding material to cause said lidding material to lift in the direction of said mold.
 42. The method of claim 41 wherein causing said lidding material to come into contact with a female thermoforming mold includes introducing a positive pressure gas into the sealed chamber.
 43. The method of claim 42 wherein introducing a positive pressure gas into the sealed chamber includes introducing a positive pressure modified atmospheric gas into said chamber.
 44. The method of claim 39 further including evacuating the ambient atmosphere from said tray.
 45. The method of claim 39 further including heat-sealing said lidding material to said tray.
 46. The method of claim 45 further including removing excess lidding from the outside perimeter of said tray.
 47. A method of packaging comprising: lifting a flexible lidding material away from a food product disposed within a preformed tray; and conforming said lidding material to the surface contours of said food product.
 48. The method of claim 47 further including heating said lidding material as it is lifted away from said food product.
 49. The method of claim 48 further including stretching said lidding material.
 50. The method of claim 49 further including cooling and shrinking said lidding material to permanently conform it to the surface contours of said food product.
 51. The method of claim 47 further including causing said lidding material to come in contact with a heated female thermoforming mold.
 52. The method of claim 47 further including heat-sealing said material to said tray.
 53. The method of claim 52 further including removing excess lidding material from the perimeter of said tray.
 54. The method of claim 47 wherein lifting said lidding material includes creating a pressure differential across said lidding material.
 55. The method of claim 54 wherein lifting said lidding material includes introducing a positive pressure modified atmospheric gas into the confines of said tray.
 56. The method of claim 55 further including evacuating ambient atmosphere from said tray.
 57. The method of claim 47 wherein conforming said lidding material to the surface contours of said food product includes introducing ambient pressure external to said lidding. 